This invention relates to electric power pick-up and supply systems for rapid transit railways and the like, and more particularly to the collector shoe arrangements and cooperable multiple conductor rails.
In the past, various types of collector shoes, arranged either singly or in multiples, have been proposed and utilized for electric railways. Single-circuit collectors are well known, for use with third rail systems to pick up power for the electric motors of railway cars. Such single phase systems have found wide-spread use in the past, but they do not compare favorably with 3-phase power equipment involving 3-phase motors which are notably more efficient and smaller in size than single phase machines.
Proposals have been made and employed, to utilize 3-phase power for railway and material-handling systems. Arrangements of this type require multiple power rails in addition to the rails or tracks engaged by the wheels of the cars or carriages. Where 3-phase power operates at high voltages there is required adequate spacing between the three power rails, and also from the rails to ground. As is well known, a delta or triangular disposition of 3-phase rails obtains the greatest separation for a given space. One proposed multiple-rail conductor system involved placing two power rails at one side of upright support members or stanchions and placing the third power rail on the other side of the support members so as to secure the desired delta configuration. With this proposal, the support members were located so as to be offset from the center line of the railway cars, and the latter carried sets of collector shoes which were in a simple delta configuration, for engagement with the conductor rails. To provide for operation of the cars in a forward direction even when turned around on the track, the cars were provided with duplicate sets of delta-configured collector shoes, one set being located to one side of the center line whereas the other set was located at the other side of the center line. Such a proposed arrangement was wasteful of space, and also resulted in a cramping of the collector shoe assemblages with the various related components. Additionally, the location of the power rails in an off-center position left something to be desired from the standpoint of flexibility. Besides this, there was encountered the problem of properly maintaining the unused set of collector shoes in properly oriented vertical position, in readiness for use when the occasion should require this.
Another problem encountered with the off-center live conductor rail system involved disposition of the power rails at switches and the like. A centralized arrangement of power rails can result in greater simplicity at those places where switches are encountered.
With prior proposals for multiple collector shoes involving offset power conductor rails it was necessary to provide for a relatively great stroke or operative movement of the shoes. When traversing switches, signal blocks and the like at high speeds the relatively great stroke required long pick-up or guide rails. The long ramps that were necessary required considerable additional space, and there also existed the possibility of cross-phasing and improper pick-up of the collector shoes.